Enhance DataGrid and ChartCanvas with KX Dashboards-style features

DataGrid:
- Column filtering with inline inputs
- Pagination with page size selector
- Column visibility toggle
- CSV export
- Row selection

ChartCanvas:
- New chart types: candlestick, radar, gauge, treemap
- Theme-aware colors (light/dark)
- Toolbox with zoom, pan, save image
- Legend support
- Data zoom controls

Author: singaraiona

src/components/canvas/DashboardCanvas.tsx

@@ -42,14 +42,16 @@ function WidgetContainer({
   onSelect: () => void;
   onRemove: () => void;
 }) {
-  const getChartType = () => {
+  const getChartType = (): 'bar' | 'line' | 'area' | 'scatter' | 'pie' | 'heatmap' | 'candlestick' | 'radar' | 'gauge' | 'treemap' => {
     const id = widget.component.id;
     if (id === 'bar-chart') return 'bar';
     if (id === 'line-chart') return 'line';
     if (id === 'area-chart') return 'area';
     if (id === 'scatter-chart') return 'scatter';
     if (id === 'pie-chart') return 'pie';
     if (id === 'heatmap') return 'heatmap';
+    if (id === 'candlestick') return 'candlestick';
+    if (id === 'treemap') return 'treemap';
     return 'bar';
   };